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2 years ago

Calculate the number of moles of C2H6 in 3.97×1023 molecules of C2H6.

Chemistry

1 answer:

Aleksandr-060686 [28]2 years ago

6 0

3.97×1023 molecules C2H6 1 mol C2H6

------------------------------------------ x ------------------------------------ = 0.66 mol C2H6

6.022 x 1023 molec. C2H6

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2.50 g of Zn is added to 5.00 g of HCl

Debora [2.8K]

Zn+2HCl ----> 2ZnCl2 + H2

For 2.50 g of Zn

Mass per mol = 2.50/molar mass of Zn = 2.50/65.38 = 0.0382 g/mol
There are two moles of ZnCl2 and total mass = 2*0.0382*molar mass of ZnCl2 = 2*0.0382*136.286 = 10.42 g

For 2 g of HCl

Mass per mol = 2/2*molar mass of HCl = 2/ (2*36.46) = 0.0274 g/mol
For the two moles of ZnCl2, mass produced = 2*0.0274*136.286 = 7.48 g

It can be noted that 2 g of HCl produced less amount of ZnCl and thus it is the limiting reagent.

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2 years ago

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Answer:

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2 years ago

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2 years ago

Why do we use moles when calculating empirical chemical formulas, but not the mass?

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3 years ago

Read 2 more answers

A sample of paper from an ancient scroll was found to contain 39.5% 14C content as compared to a present-day sample. The t1/2 fo

nirvana33 [79]

Answer

7665 years

Procedure

Let N₀ be the amount of carbon-14 present in a living organism. According to the radioactive decay law, the number of carbon-14 atoms, N, left in a dead tissue sample after a certain time, t, is given by the exponential equation:

N = N₀e^(-λt)

where λ is the decay constant which is related to half-life (T1/2) by the equation:

$\lambda=\frac{ln(2)}{t_{\frac{1}{2}}}$

Here, ln(2) is the natural logarithm of 2.

The percent of carbon-14 remaining after time t is given by N/N₀.

Using the first equation, we can determine λt.

The half-life of carbon-14 is 5,720 years, thus, we can calculate λ using the second equation, and then find t.

$\lambda=\frac{ln(2)}{5720}=1.211\times10^{-4}$

Solving the second equation for t, and using the λ we have just calculated we will have

t= 7665 years

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5 months ago